That's one of the more difficult routes in the system for saver awards. It's not at all surprising UA has nothing available so close to your desired travel dates. People plan these sorts of trips very far in advance and the saver business seats go quickly when they are made available.
Carriers will often open more award seats closer to departure if the flight has lots of seats available. For example, if you wanted to fly out this Sunday, you could fly through SFO on UA in first class for 80,000 miles. On Monday, you could travel on Air Canada in business through YVR for 80,000 miles.